Self-regulating pumping mechanism



Oct. 25, 1960 w. J. O'CONNOR 2,957,427

T SELF-REGULATING PUMPING MECHANISM Filed Dec. 28, 1956 4 Sheets-Sheet 1INVENTOR Walter J. O'Connor g Y 3W M Oct. 25, 1960 w. J. O'CONNOR2,957,427

SELF-REGULATING PUMPING MECHANISM Filed Dec. 28, 1956 4 Sheets-Sheet 2Oct. 25, 1960 w. .1. O'CONNOR SELF-REGULATING PUMPING MECHANISM 4Sheets-Sheet 3 Filed Dec. 28, 1956 Walter J. O'Connor Oct. 25, 1960 w.J. OCONNOR 2,957,427

SELF-REGULATING PUMPING MECHANISM Filed Dec. 28. 1956 4 Sheets-Sheet 4Fig .7.

INVENTOR. Walter J. O'Connor BY @XM; W

2,951,427 SELF-REGUIJAIING PUMPING MECHANISM Walter 'J. 'OConnor, 412 W.Washington Blvd, Grove City, Pa.

Filed Dec. 28, 1956, Ser. No. 631,239 Claims. (Cl. 103-420) Thisinvention relates to new self-regulating pumping mechanism having rotorand stator pump elements which are relatively axially movable inresponse to pressures opposing the pumping action force for theregulation of the same. More particularly, this invention pertains tonew mechanism utilizing helically threaded rotor and stator members withprovision for relative axial movement therebetween so as toautomatically and selectively regulate the pumping force.

In the pumping of slurries and viscous substances, for example, pressurerelief is commonly provided, particularly when positive displacementpumps are used, to prevent the development of excessive pressuredetrimental to the equipment being used, or to the operation beingconducted. In the case of some'materials such as slurries containingabrasive particles, or in the case of viscose materials, or in the caseof toxic substances, the use of valves such as pressure relief poppetvalves has given rise to a number of difficulties. With high-solidscontent slurries, solids particles discharging through such a relieftend to prevent proper reseating; with viscous materials, thecleanliness of the surroundings about the discharge side of the reliefvalve has been a' problem; particularly in connection with food andhealth-material processing industries where cleanliness isindispensable; with toxic or corrosive materials, such pressure reliefventings have had to be provided for in a manner to safeguard men andequipment from the effects of material so discharged in the courseofsystem pressure relief. Difficulties and deficiencies of'priorpractices may be overcome by utilization of my invention disclosedherein. Thus, in the event that greater than desired pressures tend tooccur, mechanism embodying my invention provides for the relative axialmovement of rotor and stator members in the 'pump element toautomatically self-regulate the maximum pressure which can be developedby the pumping action in the system. In thatway, no pressure reliefvalve provision is needed in which the material undergoing processingneeds to be dis charged from the system via any such pressure reliefoutlet. Moreover, with materials to be processed of a' characternormally imposing a high-starting torque load upon a pump, my inventionmay be used, if desired, to initiate pumping action at a relativelylower starting torque until the mechanism attains such a speed forexample as to enable it to handle the normal load involvedin such case.Rotor and stator parts for new mechanism and practices of my inventionmay have operative configurations for pumping action of the kinddisclosed in expired Patents Nos. 1,892,217 and 2,028,407.

Other objects and advantages will be apparent from the followingdescription and the accompanying drawings, which are illustrative only,in which I Figure 1 is a view in side elevation, partly in section, ofone embodiment of my new self-regulating pumping mechanism;

I Figure 2 is a view in side elevation, partlyin section,

2,957,427 Patented Oct. 25, 1960 ice of the structure shown in Figure 1with parts thereof having moved axially relative to one another forpressure regulating purposes;

Figure 3 is a plan view Figure 1;

Figure 4 is a view in longitudinal section through a further embodimentof my invention; Figure 5 is a view taken along line taken along lineIII-4H of V-V of Figure 4;

Figure 6 is a view in longitudinal section of a still further'embodimentof my invention; and

Figure 7 is a view of yetanother embodiment of'my invention.

Referring to Figures vice 10 is shown therein which may be employed inmany industries which require pumping, inclusive without limitation, forexample, of the fields of food processing, chemical compositions, fritand slip mixtures for the enameling and pottery, plasma and othermedical supplies, pharmaceuticals, petroleum base materials, to men tionbut some of the possibilities.

In device 10, a cabinet 11 may be supported on a plant floor by legs 12.A mixing receptacle 13 which may instead be only a feed hopper for thematerial which will undergo pumping action is also suitably affixed tocabinet 11. A post 14 is rigidly connected to cabinet 11 to in turnsupport one embodiment 15 of new mechanism of this invention.

Mechanism 15 may comprise a rigid frame 16 whichis secured to post 14.Frame 16 in turn is provided with. sleeves 17 fixed thereto for thereceipt of guide rods 18, guide rods 18 being adapted to slide insleeves 17. The" rear ends of rods 18 are rigidly connected to aplatform 19. An electric motor 20 is also rigidly connected toplatform19 as is a nut 21, the threads of which engagethe threads of anadjustment screw 22. Screw 22 is universally'coupled to a rod 23, thefront end of which extends through a bushing 24 outside cabinet 11 wherea handwheel 25 is affixed thereto. Motor 20 is provided with an armatureshaft 26 which is keyed to a variable diameter driving pulley 27 mountedthereon for purposes of moving a V-belt 28 when motor 20 is energized.If handwheel 25 is moved so that nut 21 and thereby motor 20 are movedtoward the rear of cabinet 11, belt 28 will separate the flanges ofdriving pulley 27 and reduce thev effective diameter thereof.Conversely, if handwh'eel 25 is rotated in the otherdirection, motor 20will be moved nearer to post 14 and belt 28 will be driven at a higherspeed for a given r.p.m. of motor 20 because of the greater eifectivedriving diameter of pulley 27. Thus, theparts just described constitutean adjustable speed construction for mechanism 10 to be run at whateverspeed is selected for the turning of a rotor 29.

Rotor 29 in the illustrated embodiment being described is made of anon-yielding material like metal and the outer surface thereof is in theform of a single male helical thread with the cross section of the rotorat any point being circular. a drive shaft 30 on which, if desired,mixer blades 31 may be adjustably and detachably mounted for serviceswhere mixing, in addition to pumping, is wanted. A detachable coupling32 has one portion connected to drive shaft 30 and the other portionconnected, to a spindle 33. Such coupling 32 may be a flexible couplingby, for example, having one part made out of a somewhat yieldablematerial, if desired, and further, may be a coupling in which the partsare fastened together so that me lifting of spindle 33 willcorrespondingly lift shaft 30, thereby separating rotor 29 axially froma cooperating pling 32 upper and lower jaw parts thereof coupled forrotation byvirtue only of the fact that the upper part is resting l to 3of the drawings, a new de- Rotor 29 is affixed to the lower end of fixedstator 34 to the desired distance, or couinthe illustrated embodimentmay have the.

on the lower part under the force tending to move spindle 33 downwardlyin a direction tending to keep substantially the entire length of rotor29 within the length of stator 34.

Spindle 33 is rotatably but not axially movable in thrust bearings 35which are fixed in place at the ends of a quill 36 having a rack portion37 on the rear iace thereof. A collar 38 fixes the location of quill 36along spindle 33, which spindle continues through and above collar 38where it is provided with a splineway 39. A land 40 in the housing onframe 16 and a bushing 44 through which the splined portion of spindle33 extends provide a guide for quill 36, in conjunction with an idlerpinion 41 meshing with rack 37 to hold quill 36 slidably mounted forlongitudinal movement without rotation of quill '36 relativeto frame 16.

A driven pulley 42 is rotated by belt 28 andis provided with a rollerbearing 43 which is held against downward movement by bushing 44. Aspline key connects pulley 42 to spindle 33 so that there can be norelative rotation therebetween although spindle 33 may move axiallythrough driven pulley 42 from a lower extreme position illustratedinFigure 1 to an upper extreme position illustrated in Figure 2. There isan opening in top of cabinet 11 which is covered by a hood 46'into whichthe top of spindle 33 may project as occasion arises. If desired, alimit switch 47, shown in dotted outline, may be provided in machine inalignment with the axis of spindle 33 and electrically connected tomotor 20 so that motor 20 is de-energized if and when spindle 33 shouldmove into its extreme upper position shown in Figure 2. On the otherhand, member 47 may have an alarm bell or light switch substitutedtherefor if desired.

An arcuate gear 48 is provided and meshes with idler pinion 41. Gear 48is fixed to a gear shaft 49 mounted in bushings in the sides of frame16, the gear shaft 49 projecting therebeyond and extending into a socket50 at the from end of a lever 51. Lever 51 extends through an opening 52in a counterweight 53 by means of which a predetermined force isselected and exerted upon gear 48 and therethrough upon rack 37, saidforce tending to move quill 36 and spindle 33 in a downward directiontoward its lowermost position as shown in Figure l, the upper end ofrack 37 and pinion 41 constituting a limit stop for any such downwardmovement. In that Figure 1 position of the new mechanism, the entireiength of rotor 29 is within and coincides substantially with the entirelength of stator 34.

Counterweight 53 is provided with a further longi- .tudinal opening 54extending .therethrough and having a female threaded portion forengagement by the threads of an adjustment screw 55. Screw 55 isconnected by a universal coupling 56, intersecting the extended axis ofshaft 49, toa rod 57 which is mounted at its front end in a bushing 58and extends through the front of cabinet 11 where it is .afiixed to ahandwheel 59. Hence, as handwheel 59 is turned in a direction whichmoves counterweight 53 to the rear, the force exerted by lever 51 upongear 48 to move quill 36 in a downward direction is correspondinglyincreased, and vice versa.

Stator 34 is preferably made of a resilient material like neoprene or itmay be made of some other'material, preferably of a pliable nature. Onthe other hand, stator 34 may also be made of a hard material providedthere is a proper ratio between the helical threads on the respectiverotor and stator. Rotor 29 comprises a single male helical thread asdescribed above. The interior surface 60 of stator 34 compries, in theillustrated embodiment, two female helical thread portions, each ofwhich has the same pitch circle at the pitch circle of the thread ofrotor 29. Moreover, the two threads forming surface 60 are 180 angulardegrees apart. Thus, the lead of the thread on rotor 29 is one-half thelead of either of the threads in stator 34.. The rotation of rotor 29,or of any thread turn thereof, in stator 34 will constitute a positivedisplacement pumping action and creating a pumping force which, by meansof my new mechanism, will not exceed a predetermined limit.

In mechanism 10, the resilient stator 34 is encased in a cylindricalshell 61 having flanges 62 and 63 for respective connect-ion to anoutlet connection 64 of receptacle 13 and a discharge fitting 65.Material pumped by pump elements 29 and 34 are forced through dischargefitting 65 into the continuing portion of the system of which mechanism10 may be a part. However, if for any reason the pressure within fitting65 rises to the selected limit determined by the setting ofcounterweight 53 along lever 51, rotor 29 will back out of stator 34axially, without wholly leaving stator 34, a distance sufiicient toreduce the pumping force exerted by the rotation of rotor 29 to keep itwithin that selected limit without cessation of pumping. As soon as'thecondition causing the pressure rise subsides, counterweight 53 will tendto return rotor 29 to its normal working position in stator 34 and,conversely, should the pumping force continue to rise, then rotor 29will back farther away from the discharge end of stator 34 until abalance is reached at the preselected force limit, which may constitutean operating position between the extreme positions respectivelyrepresented in Figures 1 and 2. In the event that the reaction pressureeffective adjacent the dischar e end 66 of rotor 29 continues to rise,rotor 29 may move into its extreme upward position shown in Figure 2whereat it, in cooperation with stator 34, exerts very little pumpingforce while at the same time acting to .bar the return of material belowend 66 into receptacle 13. As described above, an alarm or a limitswitch 47 may be provided to stop all pumping when spindle 33 reachesthe position shown in such Figure 2. It will be realized that differentmaterials will require a idifiierent optimum setting of counterweight 53and, also, that mixing equipment such as the paddles 31 will be whollydispensed with in many services and, still further, that the embodimentshown in Figures 1 to 3 may take a variety of forms without departingfrom the principles illustrated by that construction.

In starting up rotor 29, the starting resistance may be readilyovercome, if needed or desired, until the operation is fairly wellstarted either by increasing the speed of the rotor through anappropriate turning of handwheel 25 or by reducing the initial pumpingforce by bringing counterweight 53 nearer to handwheel 59 by the turningof that handwheel 59 in an appropriate direction, following which whenthe operation is fully under way the speed of rotor 29 can be reduced tothe normal operating speed if handwheel 25 had been moved, or handwheel59 can be turned to increase the force setting of counterweight 53 tothe predetermined limiting force selected for the operation so begun,respectively. It will'also be noted that the new mechanism of Figures 1to 3 can be readily cleaned and sterilized and/or taken apart formaintenance servicing if and when desired. Such cleaning is of extremeimportance in certain food and pharmaceutical processing fields. In thecase of the embodiment being described, the spindle 33' may be movedtoan upper position and the upper and lower parts of coupling 32disengaged whereupon shaft 30 and rotor 29 may be readily taken awaywhen receptacle 13, stator 34 and the pipes beginning with dischargeoutlet fitting 65 are cleaned. Similarly, the shaft 30, paddles 31 androtor 29 can be cleaned before the device is reassembled to be ready fora new operation.

In the further embodiment illustrated in Figures 4 and 5, I haveprovided a device 70 which operates in accordance with my new principledisclosed in the mechanism of Figures 1 to 3. In device 70, a headmember 71 of apump casing is provided with a port 72 to receive aflowable substance to be pumped out through a delivery member 73 havingdischarge outlet 74 therein, the outer end of delivery member 73 beingclosed by an end plate 75. A shell 76 extending between the members 7 1and 73 completes the pump casing for device 70 on which legs 77 areprovided for mounting in any desired position. A stator 78 preferably ofresilient material and having a female thread character of the typedescribed in connection with stator 34 is provided and joined to shell76 so that there is no rotation of stator 7'8 as a rotor 79 rotatesrelative thereto to exert a pumping force operative upon the materialentering port 72. Rotor 79 may also be constructed of a metal having itsouter surface burnished, if desired, and with a single male helicalthread as described in connection with rotor 29 with its lead distanceper turn equal to one-half the lead of either of the two female threadswhich together comprise the internal surface 80 of stator 78. Rotor 79is provided with a countersunk axial cylindrical recess 81 through whicha connecting rod 82 extends. The forward end of connecting rod 82extends through an opening 83 in the discharge end of rotor 79 and isprovided with an eye which extends into a seal cap 84 which is joinedthereto in articulated fashion by a pivot pin 85. Hence, as connectingrod 82 rotates, it will force rotor 79 to turn and as rotor-79 turns, itwill wobble transversely in cooperation with the adjoining portions ofsurface 80 at the time being to provide the pumping force exerted bydevice 70.

The rear end of connecting rod 82 is provided with another ball eyewhich fits into a conical socket 86 in the forward end of a drive shaft87. A rear pivot pin 88 pivotally connects the eye at the rear end ofconnecting rod 82 to drive shaft 87 at the apex of socket 86. Since theaxis of rear pivot pin 88 is at right angles to the axis of front pivotpin 85', a universal connection is provided which will accommodate thetransverse wobble or orbital movement of rotor 79 in the course of itsbeing turned by shaft 87. A stuffing box 89 isprovided in the outer endwall of member 71 for the passage therethrough of shaft 87, withsuitable packing being provided in the gland and a gland follower 90holding the packing in place in the stuffing box and also bushing shaft87. A separate antifriction hearing may be provided between follower 90and shaft 87, if desired. It will be noted that no matter what theposition may be in which device 70 is mounted, material pumped therebywill not come into contact with lubricated or other members of thedevice save those which are readily cleaned, and, if abrasive slurries,for example, are being pumped, the life of the packing in stuffing box89 will be prolonged as will shaft 87 since the pumping force is exertedin a direction away from member 71 toward member 73.

A bearing casing 91 is provided in device 70 and is rigidly connected tohead member 71 by brackets 92. Casing 91 may be rectangular in crosssection and have a rectangular slide chamber 95 for a slidable rollerthrust bearing unit 94. An opening 95 in the front wall of casing '91and an opening 96 in a back cover 97 of casing 91 permit shaft 87 toextend therethrough as shown. The rear end 98 of shaft 87 is splined forslidable coupling to a prime mover such as an electric motor or othersource of power to turn rotor 79 in the appropriate direction to developpumping force for the discharge of material through port 74. Unit 94 isprovided with a cylindrical interior surface 99 having roller thrustbearings 100 at the respective ends thereof separated by a spacer 101and maintained in position relative to each other and to the unit 94.The inner races of bearings 100 engage a necked portion 102 of shaft 87,such shaft 87 having no axial movement relative to unit 94 by virtue ofbeing secured between a shoulder 103 and lock nuts i104 engaging athreaded portion of necked portion 102.

A bracket stand 105 is rigidly affixed to the top of casing 91 topivotally support a lever 106, the lower end of which extends downwardlythrough an opening 107' in casing 91 into a keeper opening 108 in thetop of unit 94. Lever 106 is in the form of a bell crank having anoutstanding arm 109 on adjustably secured by a set screw 111 so that apreselected force can be applied to lever 106 to urge unit 94 andthereby drive shaft 87 in a direction tending tomove rotor 79 intostator 78. In the position shown in Figure 4, rotor 79 has automaticallyand axially displaced itself rearwardly relative to stator 78 to staywithin the pre-. selected force limit corresponding to the setting ofcounterweight 110, pursuant to the principle discussed hereinabove inconnection with the embodiment set forth in Figures 1 to 3, suchdisplacement correspondingly reduc:- ing the maximum pumping forceachievable by cooperation of the members 78 and 79 as when therespective lengths thereof are coincident. Thus, the device 70 isself-regulating in terms of the maximum force achievable by the pumpingaction exerted thereby, which maximum force is selective, as statedabove, in accordance with the predetermined setting of counterweight110.

A still further embodiment of my invention is illustrat ed in Figure 6,parts thereof corresponding generally in construction and functioning toparts shown in Figure 4 are provided with the same reference numeralswith the addition of a prime accent thereto. In the still furtherembodiment of Figure 6 a motor 112 when energized drives drive shaft 87through a flexible coupling 113 without, however and unlike'the casewith drive shaft 87, any axial movement of drive shaft 87 beingpossible; In the still further embodiment of Figure 6, axial move-v mentor displacement of rotor 79 relative to stator 78' is otherwise providedfor in that an axial bore 114 in rotor 79' is provided with splineways115 engaged by corresponding projections on the sides of slidable cap116. Splineways 115 are provided at the rear ends thereof with stops 117to limit the rearmost position of cap 116 toward which rearmost positioncap 116 is urged by a spring 118. The forward end of rotor 79' isprovided with an internally threaded cylinder flange 119 at the frontend of bore 114 in which a pair of threaded lock plugs 120are positionedat a preselected axial position therein to serve as a retainer for theforward end of spring 118. By adjustment of such lock plugs 120, the.force exerted by spring 118 is correspondingly adjusted. In operation,maximum pumping pressure of the Figure 6 embodiment, for a given numberof revolutions per minute of the rotor, is achieved when flange 119 isinthe dot-and-dash position illustrated in that figure. However, shouldthe pressure rise in the pipe leading from port 74 so as to tend toexert a counterforce greater than the preselected limit, the rotor 79'will move toward the position illustrated in solid lines in Figure 6 tomaintain the pumping force within the preset maximum established by theadjustment of spring 118. In this way, as in embodiments previouslydiscussed, I have provided novel means for pressure relief which do notrequire discharge of pumped material outside the system or risk ofrupture by pressure of one or more parts of a closed system in whichsuch pumping is being done.

In Figure 7, I have shown yet another embodiment of my invention andparts thereof corresponding generally in construction and functioning toparts of the embodiment illustrated in Figure 6 are provided with thesame reference numerals having however a double prime accent therewith.It will be seen that rotor 79" has an envelope which is generally in theform of the frustum of a cone with the portion of lesser diameter towarddischarge member 73". Moreover, the envelope of interior surface ofstator 78" correspondingly nar: rows. Accordingly, as and to the extentthat wear oc-. curs, the normal position of motor 79" may be movedsomewhat forwardly, that is, toward the smaller end thereof so as to'take up such wear, such adjustment being performable either byappropriate adjustment movement of threaded lock plugs 120" or by theselec-. tion of another spring 118 to provide for such take-up,

which a counterweight is In addition, the embodiment illustrated inFigure 7 is provided with a further feature in the form of means tocontrollably vary the transverse section of the rotor space opening instator 78". Thus, the crests 121 of one of the female helix threadportions comprising surface 80" have a helical passage radiallyoutwardly thereof which is occupied by a' flexible tube 122 preferablyvulcanized to the walls of such passage. A metal tube 123 of smallerdiameter than the internal diameter of tube 122 is within such flexibletube 122 throughout its length within stator 78", such metal tube 123having perforations along its length and around its circumference. Therespective ends of perforated metal tube 123 are secured to pipes 124and 125 through appropriate fittings and a fluid such as water under anappropriate pressure is pumped through one of such pipes 124125, leavingthe stator via the other, to fill tube 122 and press it radiallyoutwardly to the desired pressure extent. The same provision in theembodiment of Figure 7 is provided for the other female helical threadportions 1210 in surface 80" as shown by the tube 122a and theperforated metal tube 123a therein, the respective connections theretobeing marked 124a and 125a. In this way, the pressure within the tubes122 and 122a may be set at a lower figure during the initiation of apumping action so that starting torque requirements of device 70" arerelatively lower. There is no possibility of collapse of stator 78"because, for example, of the presence of perforated metal tubes 123 and123a. As the operation gets fully under way, the fluid pressure withinthe tubes 122' and 122a can be increased to a normal operating figurefor whatever greater preselected tightness of engagement contact betweenstator 78" and rotor 79" is desired for the particular operation. Thetubes 122 and 122a and the connections thereto may also be used to servea cooling function for the circulation of a coolant fluid therethroughin the case of operations where such may be desired or useful.

Various modifications may be made in my invention and respective ones ofthe above described embodiments, without departing from the spirit ofmy' invention or the scope of the appended claims.

I claim:

1. In a self-regulating pumping mechanism, apparatus comprising, incombination, a resilient tubular stator having double lead helicalfemale threads, a non-yielding rotor having its exterior surfacecomprising a single helical male thread, the pitch circles of saidthreads being generally equal and of uniform diameter, the lead of saidstator threads being approximately twice the lead of said rotor thread,a driving shaft operatively connected to said rotor, a spindledetachably and flexibly coupled to said driving shaft, a quill rotatablysupporting said spindle, said quill having a rack portion, a gearoperatively connected to said rack, a housing in which said quill ismounted for longitudinal movement, a counterweight operatively connectedto said gear to exert force upon said gear to bias said quill in thedirection of urging said rotor into a position substantially whollywithin said stator, means to shift the relative position of saidcounterweight to adjust the amount of force exerted by saidcounterweight upon said gear, and adjustable speed means operativelyconnected to said spindle to rotate said rotor at a preselected speed,whereby the development of a pumping force between said rotor and statoris limited by the force yieldingly exerted as a result of saidcounterweight so that said rotor will move axially relative to saidstator in a direction opposite to said firstnamed direction to maintainsaid pumping force within said limit.

2. In a self-regulating pumping mechanism, apparatus comprising, incombination, a resilient stator having a longitudinal rotor opening withits interior surface comprising helical female thread portions, a rotorhaving its exterior surface comprising one less helical thread than saidstator to cooperate with said interior surface of said stator to exert apumping force, a driving shaft operatively connected to said rotor, aflexible connection between said spindle and rotor, a spindle detachablycoupled to said driving shaft, a quill rotatably supporting saidspindle, said quill having a rack portion, a gear operatively connectedto said rack, a frame in which said quill is mounted for longitudinalmovement, adjustable forceexerting means operatively connected to saidgear to bias said quill yieldingly in the direction of moving said rotorfarther into the rotor opening in said stator, and means operativelyconnected to said spindle to rotate it and thereby said rotor wherebythe development of a pumping force between said rotor and stator islimited by the force yieldingly exerted by said first-named means.

3. In a self-regulating pumping mechanism, apparatus comprising, incombination, a stator member having a helically threaded rotor openingtherethrough, a rotor member having its exterior surface helicallythreaded to pump in said rotor opening, said stator member having onemore helical thread than said rotor member, one of said members beingresilient relative to the other, the lead of said stator threads beingapproximately twice the lead of said rotor thread, a driving shaftoperatively connected to said rotor adapted to be operatively connectedto a prime mover, means operatively connected to said shaft to bias saidshaft yieldingly in a direction to move said rotor generally axiallyinto said rotor opening, and means to rotate said shaft.

4. In a self-regulating pumping mechanism, apparatus comprising, incombination, rotor and stator pumping elements having cooperatinghelically shaped threads, said stator element having one more threadlead than said rotor element with corresponding pitches on the threadsof said elements respectively, one of said elements being pliablerelative to the other, a cylindrical recess in said rotor, a connectingrod extending at least into said recess and having one end pivotallyconnected to said rotor forwardly of the rear end of said connectingrod, a drive shaft extending axially away from the rear end of saidrotor, said connecting rod being pivotally connected to said shaftadjacent the end thereof nearer to said rotor, said pivots at saidrespective ends of said connecting rod being angularly displaced so asto be at right angles to one another for universal joint movement, apump casing enclosing said rotor and stator elements, said shaftextending through one end of said pump casing, packing means to seal theopening for said shaft through said pump casing, a bearing casing, aslidable unit in said pump casing operatively connected to said shaft topermit said rotor to move axially relative to said stator, andadjustable means operatively connected to said slidable unit to biassaid slidable unit to urge said rotor in a direction to bring the lengthof said rotor into general transverse correspondence with the length ofsaid stator.

5. In a self-regulating pumping mechanism, apparatus comprising, incombination, rotor and stator pumping elements having cooperatinghelically shaped threads, said stator element having one more threadlead than said rotor element with corresponding pitches on the threadsof said elements respectively, a connecting rod pivotally collected tosaid rotor element, a drive member positioned in generally axialrelation to said rotor element, said connecting rod being pivotallyconnected to said drive member to provide a universal connection betweensaid rotor element and said drive member, a pump casing enclosing saidrotor and stator elements, a second casing, a slidable unit connected tosaid drive member in said second casing, and means operatively connectedto said slidable unit to urge it toward said rotor element in ayieldable manner.

6. In a self-regulating pumping mechanism, apparatus comprising, incombination, rotor and stator pumping elements having cooperatinghelically shaped threads, said stator element having one more threadlead than said rotor element with corresponding pitches on the threadsof said elements respectively, one of said elements being made of pliantmaterial relative to the other of said elements, a drive member for saidrotor element, a connecting member flexibly connected between said rotorelement and said drive member, and means operatively connected to saidrotor element to yield and move said rotor element away relative to saidstator element to control the thrust force exerted by said rotorelement.

7. In a self-regulating pumping mechanism, apparatus comprising, incombination, rotor and stator pumping elements having cooperatinghelically shaped threads, said rotor having one less thread lead thansaid stator with the pitches of said threads corresponding, at least oneof said elements being made of a resilient material, a cylindrical borein said rotor, splineways in said bore, a cap adapted to slide in saidbore, said cap having projections engaging said splineways to enablesaid cap to move axially but not rotatably relative to said rotor, stopsin said bore to mark one extremity of possible movement of said cap, aspring retainer in said bore spaced from said stops in an adjustablemanner, a spring extending between said cap and said retainer, aconnecting rod pivotally connected to said cap, a drive shaft extendingaxially away from one end of said rotor, said connecting rod beingpivotally connected to said shaft in spaced relation to said cap, saidpivots of said connecting rod being angularly spaced at right angles toone another for universal joint movement, a pump casing enclosing saidrotor and stator elements, and means operatively connected to said shaftto rotate it to turn said rotor, whereby operating pressures in thedischarge from said pump casing greater than the force exerted inaccordance with the force produced by said spring will axially displacesaid rotor in a direction relative to said stator to reduce the pumpingforce which would otherwise be exerted by said rotor and stator pumpingelements in a self-regulating pressure relief action.

8. In a self-regulating pumping mechanism, apparatus comprising, incombination, a rotor and a stator having cooperating helically shapedpumping threads, said rotor having one less thread lead than said statorwith the pitches of said threads corresponding, a cylindrical bore insaid rotor, a cap, means for moving said cap axially but not rotatablyrelative to said bore and rotor, a spring retainer in said bore spacedfrom said cap, a spring extending between said cap and said retainer,and a drive member flexibly connected to said cap whereby operatingpressures in the discharge from said pump casing greater than t e orce ee e i ac o da ce i h t e shared of said spring will axially displacesaid rotor in a direction away from said stator.

9. In a self-regulating pumping mechanism, apparatus comprising, incombination, a stator member, said stator member having helicallythreaded interior surface portions forming a rotor member opening, arotor member to cooperate with said stator member, said rotor memherhaving a helically threaded surface with one less helical thread thansaid stator member to cooperate with said interior surface of saidstator member, the respective leads of said respective helical threadsbeing in the ratio of the respective number of such threads on saidstator and rotor members, means for normally maintaining said rotormember within said stator member to a predetermined extent, and yieldingmeans operatively connected to one of said members to take up relativemovement apart of said members to regulate to a predetermined maximumthe pumping force developed between said members by relative axialrotation therebetween.

10. In a self-relieving pressure differential mechanism, apparatuscomprising, in combination, a rotor member having a helically threadedsurface, a stator member having an axially extending opening for saidrotor member with the surface of said opening helically threaded inoperative correspondence with the surface of said rotor, said rotormember having one less helical thread than said stator member with thepitches of said surfaces of said respective members corresponding, meansoperatively connected to one of said members to urged them into axiallyoverlapping relation, said means further being yielding to move w'thsaid one of said members a sufficient distance at least as great as theaxial length of one pitch upon the occurrence of a predeterminedpressure in said device.

References Cited in the file of this patent UNITED STATES PATENTS Re.24,079 Mateer Oct. 25, 1955 2,028,407 Moineau I an. 21, 1936 2,369,539Delamere Feb. 13, 1945 2,532,145 Byram Nov. 28, 1950 2,545,626 MoineauMar. 20, 1951 2,612,845 Byram et a1 Oct. 7, 1952 2,691,347 Zimmer Oct.12, 1954 2,733,854 Chang Feb. 7, 1956 2,765,114 Chang Oct. 2, 19562,778,313 Hill Jan. 22, 1957 FOREIGN PATENTS 473,930 Canada May 29, 1951UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 2.957427 October 25, 1960 I Walter J. O'Connor It is h'ereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read'as corrected below Column 1, lines30 and 31, for "viscose" read viscous column 3, line 39, for "frone"read front line 71, for "at" read as column 5, line 54, for "95" ead 93column 8, lines A and 5, strike out "a spindle detachably coupled tosaid driving shaft," and insert thesame after "rotor in line 3, samecolumn 8; same column 8, line 6.2

for "collected" read connected column 10 line 29, for "urged" read urgesame column 10, line 44, list of 1 references cited under UNITED STATESPATENTS, for "Zimmer" read Signed and sealed this 6th day of June 1961(SEAL) Attest: ERNEST W. SWIDER DAVID L. LADD Attesting OfficerCommissioner of Patents

